JP2012052675A - Control apparatus, control method, and display method of oxygen combustion boiler plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control apparatus capable of deciding a mixed quantity of exhaust gas with oxygen so as to make the combustion rate and temperature match a predetermined value, in a boiler of an oxygen combustion system.SOLUTION: The control apparatus of an oxygen combustion boiler plant includes: a combustion rate calculator for calculating the combustion rate of fuel at the piping of transporting the fuel or in the vicinity of a burner outlet; a combustion temperature calculator for calculating a combustion temperature of a boiler furnace; and an oxygen flow rate and exhaust gas recirculation flow rate decision unit for deciding an exhaust gas recirculation flow rate and an oxygen flow rate that are fed to the burner and the air port so as to make the combustion rate and the combustion temperature meet the set values.

Description

  The present invention relates to a control device and a control method for an oxyfuel boiler plant.

  It has been pointed out that thermal power plants that have boilers and steam turbines as main components emit more carbon dioxide, which is a cause of global warming, than other power generation systems.

  Therefore, a method of burning with high-purity oxygen instead of using air as in the prior art when fuel is burned in a boiler has been proposed. Hereinafter, this method is called oxygen combustion, and the combustion method using air is called air combustion.

  In oxyfuel combustion, most of the exhaust gas becomes carbon dioxide, so there is no need to concentrate the carbon dioxide when recovering carbon dioxide from the exhaust gas, and the exhaust gas can be cooled as it is to liquefy and separate carbon dioxide. It is one of the effective methods for reducing carbon dioxide emissions.

  In addition, since about 80% of nitrogen in the air is not supplied to the boiler, nitrogen oxide (thermal NOx) generated from nitrogen in the air is not generated, and a reduction effect of nitrogen oxide is also expected.

  Oxyfuel boilers are burned using high-purity oxygen instead of air, but oxygen alone circulates part of the boiler exhaust gas because the flame temperature becomes too high and the burner and boiler furnace wall surfaces may be damaged. A method of mixing and burning with oxygen has been proposed.

  Patent Document 1 discloses a method of controlling the circulating gas flow rate of boiler exhaust gas so that the total heat recovery amount of the boiler becomes a target heat recovery amount, a system for supplying oxygen to the boiler main body by mixing oxygen with the circulating exhaust gas, and oxygen directly in the boiler main body. It is described that the heat recovery amount of the boiler body is controlled by changing the flow rate ratio of oxygen supplied to both systems.

  Further, a method of starting with air combustion at startup and switching to oxyfuel combustion with a predetermined load has been proposed. Patent Document 2 discloses that the outlet oxygen concentration of the boiler body is equal to the outlet oxygen concentration set value at startup. After the start-up is completed, the flow rate of oxygen supplied from the high-purity oxygen production device is adjusted so that the outlet oxygen concentration of the boiler body becomes equal to the outlet oxygen concentration set value, and the inlet oxygen concentration of the boiler body Describes a method of adjusting the exhaust gas circulation flow rate so that becomes equal to the inlet oxygen concentration set value.

JP 2007-147162 A JP 2001-336736 A

  In an oxyfuel boiler, the amount of oxygen in the supply gas and the amount of exhaust gas recirculation can be changed independently. Proper control of these quantities leads to stable and safe operation of the plant.

  If the oxygen concentration in the coal transport gas is high, combustion starts before the boiler furnace, and the coal transport piping may be damaged. Further, if the amount of oxygen supplied to the burner is small, coal may not be burned in the boiler furnace and there is a possibility of misfire. It is necessary to appropriately control the amount of mixed gas between the coal transportation gas and the combustion adjustment gas exhaust gas and oxygen so that the coal transportation piping is not damaged and misfire occurs.

  In order to operate the boiler efficiently, it is also important to maintain the combustion temperature in the boiler furnace at the design value. Since the combustion temperature in the boiler furnace depends on the gas for transporting coal, the gas for adjusting the combustion, and the gas supplied to the after-air port, it is necessary to appropriately control the mixed amount of the exhaust gas and oxygen of these gases.

  The above-mentioned patent document does not describe how to mix the exhaust gas and oxygen of the gas for coal transportation, the gas for combustion adjustment, and the gas supplied to the after-air port.

  An object of the present invention is to provide a control device capable of determining the exhaust gas recirculation flow rate and the oxygen flow rate so that the combustion speed and the combustion temperature coincide with preset values.

  Using a gas containing oxygen at a higher concentration than in air and a gas containing carbon dioxide at a higher concentration than in air, a boiler that generates fuel by burning fuel at a burner and an air port, and a gas containing the carbon dioxide In the control device of the oxyfuel boiler plant, which includes an exhaust gas circulation means for using a part of boiler exhaust gas as a circulating exhaust gas, and a carbon dioxide recovery means for recovering carbon dioxide in the exhaust gas of the boiler, the fuel is conveyed Combustion rate calculation means for calculating the combustion rate of fuel in the vicinity of the piping or burner outlet, combustion temperature calculation means for calculating the combustion temperature of the boiler furnace section, and predetermined values for setting the combustion rate and the combustion temperature. In order to satisfy, the oxygen flow rate and the exhaust gas recirculation amount determining means for determining the exhaust gas recirculation amount and oxygen amount supplied to the burner and the air port. Controller of oxyfuel combustion boiler plant, characterized in that it comprises a.

  According to the present invention, the exhaust gas recirculation flow rate and the oxygen flow rate can be determined so that the combustion rate and the combustion temperature coincide with preset values.

It is a figure explaining the structure of the control apparatus and oxyfuel boiler plant in a 1st Example of this invention. It is a figure explaining the example of arrangement | positioning of the structure of the water / steam system in an Example, the burner of a boiler furnace, and an air port. It is an operation | movement flowchart of the control apparatus of a present Example. It is a figure explaining the Example of the combustion speed calculation means and combustion temperature calculation means in the control apparatus of a present Example. It is a figure explaining the Example of the oxygen flow volume and exhaust gas recirculation amount determination means of a present Example. It is a figure explaining the operation example of the control apparatus of the 1st Example of this invention. It is a figure explaining the screen displayed on the image display apparatus in the control apparatus of 1st Example of this invention. It is a figure explaining the structure of the control apparatus and oxyfuel boiler plant in the 2nd Example of this invention. It is a figure explaining the Example of the fuel flow volume estimation means of a present Example. It is a figure explaining the operation example of the control apparatus of the 2nd Example of this invention.

  The first embodiment will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention taking a power plant using coal as fuel as an example. The control device 400 of the present invention receives the process value measurement information 1 from the plant to be controlled, and uses this to perform a preprogrammed operation in the control device 400 to perform an operation command signal (control) to the oxyfuel boiler plant 100. Signal). The plant controls the state of the plant by operating an actuator such as a valve opening or a damper opening in accordance with the received operation command signal.

  The present embodiment is a thermal power plant having a boiler 200 and a steam turbine 300 driven by steam generated by the boiler 200 as main components (a generator is not shown). The control device 400 receives a load request command from the central power supply command station, and controls the plant to a designated load (power generation output) state based on this command. By adjusting the valve opening degree of the steam control valve 254, the steam flow rate of the main steam 251 guided to the turbine 300 changes, and the power generation output changes.

  In addition, the water / steam system includes a condenser 310 that cools the steam emitted from the steam turbine 300 into a liquid, and a water supply pump 320 that feeds water cooled by the condenser 310 back to the boiler 200 as boiler feed water. There is. Although not shown in the drawings, an actual plant also includes a feed water heater that preheats boiler feed water using a part of steam (extracted air) extracted from an intermediate stage of the steam turbine 300 as a heating source.

On the other hand, the system of exhaust gas 380 discharged from the boiler includes a gas preheater 330, an exhaust gas treatment device 340 for purifying exhaust gas, and a CO ₂ recovery device 350 (cooling dioxide) that cools and liquefies carbon dioxide in the exhaust gas. And a chimney 370 that discharges a nitrogen / oxygen main gas 351, which is a gas mainly composed of the remaining nitrogen and oxygen after recovering carbon dioxide.

  The present embodiment includes an oxyfuel combustion boiler and an oxyfuel combustion boiler that use a gas containing high-purity oxygen instead of air, whereas a conventional boiler burns fuel with air. Intended for plants.

  Therefore, as shown in FIG. 1, an oxygen production apparatus 360 for producing high-concentration oxygen by separating air into a nitrogen-based gas and an oxygen-based gas is provided. The oxygen production apparatus is a system in which air is cooled and separated using the difference between the boiling points of oxygen and nitrogen. This embodiment does not depend on the oxygen production method, and may be another method such as a membrane separation method that uses a difference in size between nitrogen molecules and oxygen molecules.

  The oxygen production apparatus 360 separates the air 363 into a high-purity oxygen gas 362 and a nitrogen-based nitrogen-based gas 361, and the nitrogen-based gas 361 is released from the chimney 370 to the atmosphere.

  If combustion is performed using only high-purity oxygen instead of air, the temperature of the flame becomes too high, and there is a possibility that the burner or boiler wall surface that burns fuel may be damaged. Therefore, the high-purity oxygen gas 362 produced by the oxygen production apparatus 360 is mixed with the circulating exhaust gas 390 that is part of the exhaust gas discharged from the boiler and supplied to the burner 210.

  Circulating exhaust gas 390 takes out part of the gas after being purified by exhaust gas treatment device 340 and raises the temperature by gas preheater 330. The flow rate of the circulating exhaust gas is adjusted by changing the opening degree of the circulating exhaust gas flow rate adjustment valve 391.

  Coal 398 as fuel is sent to a coal pulverizer 397 (mill) via a fuel supply amount adjustment valve 399. It is converted into powder (pulverized coal) by the coal pulverizer 397, conveyed by gas, and supplied to the burner 210.

  The burner 210 is supplied with a mixture 396c of coal and coal transport gas and a gas 396b for combustion adjustment. Further, an after air port 220 is disposed above the burner 210, and a gas 396 a is supplied to the after air port 220.

  The gas for transporting coal, the gas for adjusting combustion, and the gas supplied to the after-air port are mixed gases of exhaust gas and oxygen. The amount of exhaust gas and oxygen to be mixed can be controlled by adjusting the oxygen flow rate adjustment valve 211 (211a, 211b, 211c) and the exhaust gas recirculation amount adjustment valve 213 (213a, 213b, 213c). Moreover, exhaust gas and oxygen are mixed by the gas mixing part 395 (395a, 395b, 395c).

  Next, the configuration of the boiler will be described.

  Since a furnace having a burner for burning fuel has a high temperature inside the furnace, there is a cooling wall called a water wall 230 that cools the entire wall surface and collects the heat of the combustion gas. In the boiler 200, there are other heat exchangers including a economizer 290, a primary superheater 280, a secondary superheater 240, a tertiary superheater 250, and a quaternary superheater 260. Is recovered to produce high-temperature steam.

  Although not shown in the figure, the plant has many sensors for measuring gas composition, temperature, pressure, steam temperature, pressure, etc., and this measurement result is measured information. 1 is transmitted to the control device 400.

  As shown in FIG. 2 (a), as steam flow, boiler feed water is first guided to the economizer 290, and then the water wall 230, the primary superheater 280, the secondary superheater 240, and the tertiary superheater 250. , And the fourth superheater 260 in this order, the temperature is raised, and the main steam 251 enters the steam turbine 300. In this cycle, the steam that has worked in the high-pressure steam turbine 300 becomes liquid in the condenser 310 and is sent again to the boiler by the feed water pump 320. As shown in FIG. 2 (b), a plurality of boiler burners 210 are installed in the horizontal direction before and after the furnace in a plurality of stages in the height direction, and a plurality of after air ports are arranged in the horizontal direction before and after the furnace. It is common. Hereinafter, the height at which the after-airport is disposed is referred to as the upper portion of the furnace, and the height at which the burner is disposed is referred to as the lower portion of the furnace.

  Next, the configuration and function of the control device 400 relating to the present embodiment will be described. The control device 400 basically controls the plant based on a load request command from the central power supply command station. The purpose of the control device of the present embodiment is to appropriately control the amount of mixed exhaust gas and oxygen in coal transport gas, combustion adjustment gas, and gas supplied to the after-air port. The control logic is described.

  If the oxygen concentration in the coal transportation gas is high, combustion starts before the boiler furnace, and the coal transportation piping may be damaged. In addition, if the amount of oxygen supplied to the burner 210 is small, coal may not be burned in the boiler furnace and misfire may occur. It is necessary to appropriately control the mixing amount of the coal transportation gas and the exhaust gas of the gas for combustion adjustment and oxygen so that the coal transportation piping is not damaged and misfire occurs.

  In order to operate the boiler efficiently, it is also important to maintain the combustion temperature in the boiler furnace at the design value. Since the combustion temperature in the boiler furnace depends on the gas for transporting coal, the gas for adjusting the combustion, and the gas supplied to the after-air port, it is necessary to appropriately control the mixed amount of the exhaust gas and oxygen of these gases.

  Therefore, the control device 400 of the present embodiment includes a combustion rate calculation unit 500 and a combustion temperature calculation unit 600, and determines the mixing amount of exhaust gas and oxygen so that the combustion rate and the combustion temperature coincide with preset values. To do.

  By controlling the combustion speed of the coal conveying gas and coal and the gas burning rate of the burner part, it is possible to prevent combustion from starting before the boiler furnace and misfire. In addition, the boiler is operated efficiently by controlling the combustion temperature in the boiler furnace.

  The combustion rate calculation unit 500 and the combustion temperature calculation unit 600 use the measurement information 1 and the external input signal 2 from the external input device 410 including the keyboard 411 and the mouse 412, respectively, to calculate the combustion rate of the combustion rate calculation unit 500. A combustion speed 3 as a result and a combustion temperature 4 as a combustion temperature calculation result of the combustion temperature calculation means 600 are output. The combustion speed 3 and the combustion temperature 4 are output to the image display device 420, and the combustion speed and the combustion temperature can be monitored in real time.

  The oxygen flow rate and exhaust gas recirculation amount determination means 700 for determining the oxygen flow rate and the exhaust gas flow rate uses the combustion speed 3, the combustion temperature 4, the external input signal 2 and the measurement information 1 to determine the oxygen flow rate command value 5 and the exhaust gas recirculation amount. The circulation amount command value 6 is output.

  The oxygen flow rate control valve control means 800 includes an oxygen flow rate control valve 211a, a gas for coal transportation, a gas for combustion adjustment, and an oxygen flow rate control valve 211a, so that the oxygen flow rate contained in the gas supplied to the after-air port matches the oxygen flow rate command value 5. The operation signal 7 of 211b, 211c is output. Further, the exhaust gas recirculation amount control valve control means 810 is configured so that the exhaust gas flow rate contained in the coal transport gas, the combustion adjustment gas, and the gas supplied to the after air port matches the exhaust gas recirculation flow rate command value 6. An operation signal 8 for the exhaust gas recirculation amount control valves 213a, 213b, and 213c is output.

  As described with reference to FIG. 2B, the boiler is provided with a plurality of burners and after-air ports. Although the piping of oxygen and exhaust gas becomes complicated and many flow control valves are necessary, in order to realize finer control, the oxygen amount and exhaust gas amount for each stage or each line are adjusted respectively. It is also possible.

  An operation flowchart of the control device 400 is shown in FIG. As shown in FIG. 3, this flowchart is executed by combining Steps 1000, 1010, 1020, and 1030.

  First, in step 1000, the measurement information 1 is acquired and taken into the control device 400. In step 1010, the combustion speed calculation means 500 and the combustion temperature calculation means 600 are operated to calculate the combustion speed 3 and the combustion temperature 4. In step 1020, the oxygen flow rate and exhaust gas recirculation amount determining means 700 is operated, and the oxygen flow rate command value 5 and the exhaust gas recirculation flow rate command value 6 are calculated. In step 1030, the oxygen flow rate control valve control means 800 and the exhaust gas recirculation amount control valve control means 810 are operated, and the operation signal 7 and the operation signal 8 are transmitted to the oxyfuel boiler plant 100 and the flow rate control valves (211a, 211b). , 211c, 213a, 213b, 213c). Steps 1000 to 1030 are repeatedly performed at a period for acquiring the measurement information 1 or at a preset period.

  Next, examples of the combustion rate calculation means 500 and the combustion temperature calculation means 600 will be described with reference to FIG.

  As shown in FIG. 4 (a), the combustion rate calculation means 500 includes a combustion rate calculation model 510.

  The combustion speed calculation model 510 calculates the combustion speed of the coal supply system and the combustion speed of the burner section based on the fuel information, gas information, and design information. Here, the fuel information is an amount indicating characteristics of the fuel (coal) such as fuel properties, fuel concentration, fuel particle size, and fuel temperature. The gas information is an amount indicating the characteristics of the gas, such as gas concentration, gas properties (specific heat, etc.), gas components (oxygen content, etc.). The design information is an amount indicating the characteristics of the plant such as the shape of the burner and the shape of the boiler.

  Using the fuel information, gas information, and design information, the combustion rate calculation model 510 calculates the combustion rate using, for example, a three-dimensional combustion numerical analysis technique. Here, the three-dimensional combustion analysis technique is a technique in which the burner and the boiler are divided into three-dimensional meshes, and the combustion state is numerically analyzed based on a physical equation with each mesh. In the present embodiment, the method of the three-dimensional combustion analysis is not characteristic, and a known analysis technique can be used. Therefore, a specific calculation algorithm is omitted here. The combustion speed calculation model 510 stores the results of the above-described three-dimensional combustion analysis for a plurality of fuel information, gas information, and design information in a database, and is most suitable for the current operating conditions. It can also be configured to output a calculation result.

  As shown in FIG. 4B, the combustion temperature calculation means 600 is composed of a combustion rate calculation model 610. The combustion rate calculation model 610 calculates the combustion temperature of the boiler furnace in the same manner as the combustion temperature calculation model 510 described above.

  Next, an embodiment of the oxygen flow rate and exhaust gas recirculation amount determining means 700 will be described with reference to FIG. In FIG. 5, “burner primary” means a gas for transporting coal, “burner secondary” means a gas for combustion adjustment, and “AAP” means a gas supplied to the after-air port.

  The adder / subtractor 730 is a module that adds signals indicated by a symbol “+” in the figure and subtracts a signal indicated by a symbol “−”. The function generator 710 (Function Generator) is a module that outputs a function f (x), where x is an input signal. The proportional-integral controller 720 is a module that outputs the result of proportional-integral calculation of Px ′ + (1 / I) ∫x′dt, where x ′ is an input signal. Here, P is a proportional gain, and I is an integration time.

  The set values 1 to 6 are values set by the operator using the external input device 410. Set value 1 is the target value of the coal feed combustion rate, Set value 2 is the target value of the burner section combustion rate, Set value 3 is the target value of the boiler inlet oxygen average concentration, Set value 4 is the target value of the furnace upper combustion temperature, The set value 5 is a target value for the furnace lower combustion temperature, and the set value 6 is a target value for the boiler outlet oxygen average concentration.

  The function generator 710 outputs a reference amount for the exhaust gas and the oxygen flow rate based on the load request signal. The function generator 710a is a reference value for the burner primary exhaust gas recirculation amount, the function generator 710b is the reference value for the burner secondary exhaust gas recirculation amount, the function generator 710c is the reference value for the total exhaust gas recirculation amount, and the function generator 710d. Is a reference value of the AAP oxygen flow rate, the function generator 710e is a reference value of the burner secondary oxygen flow rate, and the function generator 710f is a reference value of the total oxygen flow rate.

  Proportional integral controller 720 operates to correct each exhaust gas amount and oxygen flow rate so that the combustion speed, combustion temperature, and oxygen concentration match the target values.

  The proportional integral controller 720a corrects the burner primary exhaust gas recirculation amount so that the coal feed combustion speed matches the set value. The proportional integral controller 720b corrects the burner secondary exhaust gas recirculation amount so that the burner portion combustion speed matches the set value. The proportional integral controller 720c corrects the total amount of exhaust gas recirculation so that the boiler inlet oxygen average concentration matches the set value. The AAP exhaust gas recirculation amount is determined by subtracting the burner primary exhaust gas recirculation amount and the burner secondary exhaust gas recirculation amount from the corrected exhaust gas recirculation amount.

  The proportional integration controller 720d corrects the AAP oxygen flow rate so that the furnace upper combustion temperature matches the set value. The proportional integration controller 720e corrects the burner secondary oxygen flow rate so that the lower furnace combustion temperature matches the set value. The proportional integration controller 720f corrects the total oxygen flow rate so that the boiler outlet oxygen average concentration matches the set value. The burner primary oxygen flow rate is determined by subtracting the AAP oxygen flow rate and the burner secondary oxygen flow rate from the corrected oxygen flow rate.

  The method of implementing the oxygen flow rate and exhaust gas recirculation amount determining means 700 is not limited to the logic shown in FIG. 5, but the exhaust gas amount and oxygen flow rate are adjusted so that the combustion speed and combustion temperature coincide with the target values. Any logic can be used.

  Next, an example of a result obtained by operating the control device according to the first embodiment of the present invention will be described with reference to FIG. In this embodiment, control of the coal feed combustion speed will be described.

  Prior to time t1, the proportional integral controller is not operated, and the oxygen flow rate and the exhaust gas flow rate become reference amounts based on the load request command. It is assumed that the combustion rate of the coal supply system has changed in a state higher than the set value.

  By operating the proportional-plus-integral controller at time t1, the exhaust gas recirculation amount increases, and the coal feed combustion speed matches the set value. By using the control device of the present invention, the combustion speed can be controlled as in this embodiment. Although not described with reference to the drawings, the combustion temperature can also be controlled as in this embodiment.

  FIG. 7 is a diagram illustrating an example of a screen displayed on the image display device 420.

  In the display column 431, the calculation result and set value of the combustion rate of the coal supply system and the burner section are displayed. Moreover, the range of the combustion speed which does not ignite by a coal supply system, and the range of the combustion speed which does not misfire by a burner part are each displayed as a recommended range. By constantly monitoring these pieces of information, it can be confirmed whether the plant is operating safely. In addition, the setting value of the combustion speed can be changed by inputting the setting value of the combustion speed in the column 432 using the external input device 410. This changed value is reflected in the values of the setting value 1 and the setting value 2 in FIG.

  In the display column 433, the calculation result and set value of the combustion temperature of the upper part of the furnace and the lower part of the furnace are displayed. Moreover, the range of the combustion temperature which can be operated efficiently is displayed as a recommended range. By constantly monitoring these pieces of information, it can be confirmed whether or not the plant is operating with high efficiency. In addition, the setting value of the combustion speed can be changed by inputting the setting value of the combustion temperature in the column 434 using the external input device 410. This changed value is reflected in the setting value 4 and the setting value 5 in FIG.

  In the display column 430, a message indicating that there is no problem if the calculated value or the set value is within a predetermined recommended range is displayed. If the calculated value or the set value deviates from the recommended range, an error is displayed.

  As described above, in this embodiment, the information on the combustion temperature and the combustion speed is provided to the operator in real time, and the monitoring operation of the plant operation state can be supported.

  In addition, in this embodiment, the risk of misfire or piping damage can be reduced, so that the stability and safety of operation are improved. In addition, the plant can be operated efficiently.

  Furthermore, by improving the reliability of an oxyfuel boiler plant suitable for carbon dioxide recovery, it is possible to contribute to the reduction of carbon dioxide emissions, which is one of the causes of global warming.

  Note that the operation state of the plant of FIG. 6 may be displayed on the image display device 420. In the example of FIG. 6, the coal supply combustion speed is compared with the burner primary exhaust gas recirculation amount / burner primary oxygen flow rate. In this way, by comparing the combustion rate or combustion temperature with the exhaust gas recirculation amount or the oxygen amount, the operator can know the correspondence between the combustion speed / temperature and the exhaust gas recirculation amount / oxygen amount. Can help to understand. In FIG. 6, the horizontal axis is time and the trend graph is used for display, but numerical display may be used.

  In the example of FIG. 6, when the combustion rate of the coal feed system is displayed in comparison with the burner primary exhaust gas recirculation amount / burner primary oxygen flow rate, the time axis is common to both at the time of starting PI operation. It is displayed. For example, in FIG. 6, it is possible to comprehend the convergence time of fluctuations in the coal supply combustion speed and the convergence time of fluctuations in the burner primary exhaust gas recirculation amount. In this way, when comparing the combustion rate / temperature with the exhaust gas recirculation / oxygen amount, the time axis can be used as a standard display common to both, so that both relationships in time series can be grasped. it can.

  In the example of FIG. 6, the PI operation is started as the reference display common to both. However, the present invention is not limited to this, and the start point of the change in the coal feed combustion speed is set as a reference, or the set value of the coal feed combustion speed is set. It is good also as making it display on the basis of the performed time. As a result, it is possible to grasp the relationship between the exhaust gas recirculation amount and the oxygen amount starting from changes in the combustion speed and the combustion temperature.

  Further, the display of FIG. 6 has been described on the assumption of the combustion rate calculation means 500, the combustion temperature calculation means 600, the oxygen flow rate and the exhaust gas recirculation amount determination means 700 of FIG. 1, but is not limited thereto. The oxygen flow rate and exhaust gas recirculation amount determining means 700 were calculated using measured values obtained by installing a measuring device instead of the combustion speed 3 and the combustion temperature 4 calculated by the combustion speed calculating means 500 and the combustion temperature calculating means 600. It is good also as displaying using the measured value which installed the measuring device instead of the oxygen flow rate command value 5, the exhaust gas recirculation amount command value 6, and the operation signals 7 and 8 based on them.

  As described above, using a gas containing oxygen at a higher concentration than in air and a gas containing carbon dioxide at a higher concentration than in air, a boiler that generates steam by burning fuel in a burner and an air port; In a control apparatus for an oxyfuel boiler plant comprising exhaust gas circulation means for using a part of boiler exhaust gas as gas containing carbon dioxide as circulating exhaust gas, and carbon dioxide recovery means for recovering carbon dioxide in the exhaust gas of the boiler A combustion rate calculating means for calculating a combustion rate of fuel in the vicinity of a pipe for conveying fuel or a burner outlet based on measurement information of the oxyfuel boiler plant and a predetermined calculation method, and measurement of the oxyfuel boiler plant Combustion temperature calculation means for calculating the combustion temperature of the boiler furnace section based on the information and a predetermined calculation method, and the combustion speed And the amount of exhaust gas recirculation supplied to the burner and the air port based on the combustion speed, the combustion temperature, the set value, and a predetermined calculation method so that the combustion temperature satisfies a predetermined set value. The exhaust gas recirculation flow rate and the oxygen flow rate are determined by a control device having oxygen flow rate and exhaust gas recirculation amount determination means for determining the amount of oxygen and oxygen so that the combustion speed and the combustion temperature coincide with preset values. Can do.

  In addition, as described above, using a gas containing oxygen at a higher concentration than in air and a gas containing carbon dioxide at a higher concentration than in air, a boiler that generates steam by burning fuel at a burner and an air port; Control of an oxyfuel boiler plant comprising exhaust gas circulation means for using a part of boiler exhaust gas as circulating exhaust gas as gas containing carbon dioxide, and carbon dioxide recovery means for recovering carbon dioxide in the exhaust gas of the boiler In the display method of the apparatus, comprising: a database that records the combustion rate or combustion temperature of the fuel; and a database that records the amount of exhaust gas recirculation or the amount of oxygen supplied to the burner or the air port, the combustion rate or the combustion By the display method of the control device that displays the temperature and the amount of exhaust gas recirculation or the amount of oxygen in contrast, And degree, the relationship between the amount of exhaust gas recirculation, the oxygen can be grasped.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  The difference from FIG. 1 is that a fuel flow rate predicting means 900 is mounted on the control device 400.

  The fuel flow rate supplied to the boiler is controlled to maintain the steam temperature and the power generation output. Therefore, the fuel flow rate may change when the power generation output is changed. When the fuel flow rate changes, the combustion speed and the combustion temperature also change. Following this change, it is necessary to change the oxygen flow rate in order to maintain the combustion speed and the combustion temperature. However, since there is a dead time or a delay time in the operation of the oxygen production apparatus 360, the oxygen flow rate may not be changed greatly immediately. In order to solve this problem, the control device according to the second embodiment of the present invention predicts a change in the fuel flow rate, and controls the oxygen flow rate in advance based on the prediction result. Thereby, even when the fuel flow rate is changed, the combustion speed and the combustion temperature can be maintained at the set values. In order to realize such control, a fuel flow rate predicting means 900 is mounted on the control device of the present invention. The predicted fuel flow value 5 output from the fuel flow prediction unit 900 is input to the combustion rate calculation unit 500 and the combustion temperature calculation unit 600. Combustion rate calculation means 500 and combustion temperature calculation means 600 output predicted values of combustion speed and combustion temperature based on the predicted fuel flow rate.

  FIG. 9A is a drawing for explaining an embodiment of the fuel flow rate predicting means 900. The fuel flow rate predicting means 900 is constructed by combining a boiler model 910 that simulates the characteristics of the boiler and a control model 920 that simulates the control operation. The control model 920 outputs an operation condition 930 such as a fuel flow rate to the boiler model 910. The boiler model 910 calculates the steam temperature and the power generation output based on the operation condition 930 and outputs the calculation result 940 to the control model 920. By operating the boiler model 910 and the control model 920, it is possible to predict what value the fuel flow rate for controlling the steam temperature and the power generation output will be in the future. The measurement information 1 is used for adjusting the boiler model 910 and creating initial conditions for calculation.

  FIG. 9B is a diagram for explaining an embodiment of the oxygen flow rate and exhaust gas recirculation flow rate determining means 700. FIG. 9B shows only the logic for controlling the AAP oxygen flow rate. The difference from the logic for controlling the AAP oxygen flow in FIG. 5 is that a preceding control block 740 is added. In the advance control block 740, the AAP oxygen flow rate is controlled in advance so that the predicted upper furnace combustion temperature value calculated based on the predicted fuel flow rate matches the set value. A preceding control block is also added to the logic that controls other flow rates. As a result, the oxygen production apparatus 360 can be controlled in consideration of dead time and delay time, and the combustion temperature is prevented from deviating from the target value.

  In this embodiment, predicted values of the fuel flow rate, the combustion speed, and the combustion temperature can be displayed on the image display device 420.

  Next, the result of operating the control device according to the second embodiment of the present invention will be described with reference to FIG. In this embodiment, control of the furnace upper combustion temperature will be described.

  As described above, the fuel flow rate changes in order to maintain the steam temperature and the power generation output. When the control is performed without using the fuel flow rate predicting means 900, the follow-up of the oxygen flow rate is delayed, so that the combustion temperature changes greatly.

  On the other hand, by predicting the future value of the fuel flow rate using the fuel flow rate predicting means 900 and controlling the oxygen flow rate accordingly, the change in the combustion temperature can be suppressed. Although the description with reference to the drawings is omitted, it is possible to suppress the change in the combustion speed as in the present embodiment.

  As described above, it has a fuel flow rate predicting means for predicting a future value of the fuel flow rate based on a boiler model for simulating the characteristics of the boiler and a control model for simulating the control operation to the boiler. The calculating means outputs a predicted value of the combustion rate or combustion temperature based on the future value of the fuel flow rate, and the oxygen flow rate and exhaust gas recirculation amount determining means is based on the predicted value of the combustion rate or the predicted value of the fuel flow rate. Even when the fuel flow rate is changed by the control device that determines the oxygen flow rate and the exhaust gas recirculation amount by the advance control, the combustion speed and the combustion temperature can be maintained at the set values.

  As described above, since the combustion speed and the combustion temperature can be controlled to desired values (set values) by using the control device according to each embodiment of the present invention, the risk of misfire, pipe damage, and the like can be reduced. As a result, driving stability and safety are improved. In addition, the plant can be operated efficiently. Furthermore, the oxyfuel boiler can be operated while monitoring the combustion speed and the combustion temperature.

  By the way, the recent progress of global warming is becoming a serious situation, and there is a strong demand for reduction of greenhouse gas emissions such as carbon dioxide. It has been pointed out that thermal power plants that generate electricity by generating steam from the heat of burning fuel emit more carbon dioxide than other power generation methods. On the other hand, global power demand continues to show an increasing trend, and it is also true that thermal power generation plays an important role as a power supply facility from the viewpoint of stable power supply.

  According to each embodiment of the present invention, since it becomes possible to operate safely and stably, it becomes a thermal power generation system that can be expected to greatly reduce carbon dioxide emissions, which is the greatest merit of the oxyfuel boiler system, It becomes possible to achieve both environmental conservation.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. In addition, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Further, each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, files, measurement information, and calculation information for realizing each function is stored in a recording device such as a memory, a hard disk, or an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD. Can be put in. Therefore, each process and each configuration can realize each function as a processing unit or a program module.

  Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

  INDUSTRIAL APPLICABILITY The present invention can be used for an oxyfuel boiler system that can be expected to significantly reduce carbon dioxide emissions.

DESCRIPTION OF SYMBOLS 1 Measurement information 2 External input signal 3 Combustion speed 4 Combustion temperature 5 Oxygen flow command value 6 Exhaust gas recirculation command value 7, 8 Operation signal 100 Oxyfuel boiler plant 200 Boiler 210 Burner 211 Oxygen flow control valve 213 Exhaust gas recirculation control Valve 220 After-air port 230 Water wall 240 Secondary superheater 250 Third superheater 251 Main steam 254 Steam control valve 260 Fourth superheater 280 Primary superheater 290 Carbon-saving device 300 Steam turbine 310 Condenser 320 Water feed pump 330 Gas Preheater 340 Exhaust gas treatment device 350 CO ₂ recovery device 351 Nitrogen / oxygen main gas 360 Oxygen production device 361 Nitrogen main gas 362 High purity oxygen gas 363 Air 370 Chimney 380 Exhaust gas 390 Circulating exhaust gas 391 Circulating exhaust gas flow rate adjustment valve 395 Gas mixing section 397 Coal crusher 398 Coal 399 Fuel Supply amount adjustment valve 400 Control device 410 External input device 411 Keyboard 412 Mouse 420 Image display device 500 Combustion speed calculation means 600 Combustion temperature calculation means 700 Oxygen flow rate and exhaust gas recirculation amount determination means 800 Oxygen flow rate control valve control means 810 Exhaust gas recirculation Quantity control valve control means 900 Fuel flow rate prediction means

Claims (12)

Using a gas containing oxygen at a higher concentration than in air and a gas containing carbon dioxide at a higher concentration than in air, a boiler that generates fuel by burning fuel at a burner and an air port, and a gas containing the carbon dioxide As an exhaust gas circulation means for using a part of boiler exhaust gas as circulating exhaust gas, and a carbon dioxide recovery means for recovering carbon dioxide in the exhaust gas of the boiler, a control device for an oxyfuel boiler plant,
Based on the measurement information of the oxyfuel boiler plant and a predetermined calculation method, combustion speed calculation means for calculating the fuel combustion speed in the vicinity of the pipe for conveying the fuel or the burner outlet,
Combustion temperature calculation means for calculating the combustion temperature of the boiler furnace section based on the measurement information of the oxyfuel boiler plant and a predetermined calculation method;
Based on the combustion speed, the combustion temperature, the set value, and a predetermined calculation method, the exhaust gas supplied to the burner and the air port is reconstituted so that the combustion speed and the combustion temperature satisfy a predetermined set value. An oxygen combustion boiler plant control apparatus comprising oxygen flow rate and exhaust gas recirculation amount determination means for determining the amount of circulation and the amount of oxygen. In the control apparatus of the oxyfuel boiler plant according to claim 1,
The combustion rate calculation means and the combustion temperature calculation means are:
An oxyfuel boiler characterized by comprising a model for calculating combustion speed and combustion temperature based on fuel information indicating fuel characteristics, gas information indicating gas characteristics, and design information indicating plant characteristics Plant control device. In the control apparatus of the oxyfuel boiler plant according to claim 1,
In the oxygen flow rate and exhaust gas recirculation amount determining means,
A processing unit that determines the exhaust gas recirculation amount of the gas used for fuel transfer so that the combustion speed of the piping that transports the fuel matches the set value, and the combustion speed in the vicinity of the burner outlet matches the set value. From the processing unit that determines the exhaust gas recirculation amount of the gas for combustion adjustment supplied to the burner, and the total amount of exhaust gas recirculation amount determined so that the boiler inlet oxygen average concentration matches the set value, the fuel transfer and burner A processing unit for determining the exhaust gas recirculation amount of gas supplied to the air port by reducing the total amount of exhaust gas recirculation amount used for combustion adjustment of
A processing unit that determines the oxygen flow rate of the gas supplied to the air port so that the combustion temperature at the upper part of the furnace matches the set value, and for combustion adjustment that supplies the burner so that the combustion temperature at the lower part of the furnace matches the set value The total amount of oxygen flow supplied to the air port and combustion adjustment gas is subtracted from the total amount of oxygen flow determined so that the average oxygen concentration at the boiler outlet matches the set value. Thus, a control device for an oxyfuel boiler plant comprising a processing unit for determining an oxygen flow rate of a gas used for transporting fuel. In the control apparatus of the oxyfuel boiler plant according to claim 1,
An image display device for displaying the results calculated by the combustion speed calculation means and the combustion temperature calculation means, the set values of the combustion speed and the combustion temperature, and the recommended ranges of the combustion speed and the combustion temperature on the same screen; A control device for an oxyfuel boiler plant. In claim 1,
A fuel flow rate predicting means for predicting a future value of the fuel flow rate based on a boiler model for simulating the characteristics of the boiler and a control model for simulating a control operation to the boiler, the combustion speed calculating means or the combustion temperature calculating The means outputs a predicted value of the combustion rate or combustion temperature based on the future value of the fuel flow rate, and the oxygen flow rate and exhaust gas recirculation amount determining means outputs the predicted value of the combustion rate or the predicted value of the fuel flow rate. Based on the previous control, oxygen flow rate and exhaust gas recirculation amount are determined.
A control device for an oxyfuel boiler plant, characterized by that. Using a gas containing oxygen at a higher concentration than in air and a gas containing carbon dioxide at a higher concentration than in air, a boiler that generates fuel by burning fuel at a burner and an air port, and a gas containing the carbon dioxide In the control method of the control device of the oxyfuel boiler plant comprising exhaust gas circulation means for using a part of boiler exhaust gas as circulating exhaust gas, and carbon dioxide recovery means for recovering carbon dioxide in the exhaust gas of the boiler,
The control device is
Based on the measurement information of the oxyfuel boiler plant and a predetermined calculation method, calculate the combustion speed of the fuel in the piping for conveying the fuel, or the vicinity of the burner outlet, and the combustion temperature of the boiler furnace section,
Based on the combustion speed, the combustion temperature, the set value, and a predetermined calculation method, the exhaust gas supplied to the burner and the air port is reconstituted so that the combustion speed and the combustion temperature satisfy a predetermined set value. Determine the amount of circulation and the amount of oxygen
A control method for an oxyfuel boiler plant, characterized in that: In the control method of the oxyfuel boiler plant according to claim 6,
A control method for an oxyfuel boiler plant, characterized in that a combustion rate and a combustion temperature are calculated based on fuel information indicating fuel characteristics, gas information indicating gas characteristics, and design information indicating plant characteristics. In the control method of the oxyfuel boiler plant according to claim 6,
The exhaust gas recirculation amount of gas used for fuel transfer is determined so that the combustion speed of the piping that transports the fuel matches the set value, and supplied to the burner so that the combustion speed near the burner outlet matches the set value The exhaust gas recirculation amount of the combustion adjustment gas to be used is determined and used for fuel transfer and burner combustion adjustment from the total amount of exhaust gas recirculation amount determined so that the boiler inlet oxygen average concentration matches the set value By reducing the total amount of exhaust gas recirculation, the exhaust gas recirculation amount of the gas supplied to the air port is determined.
The oxygen flow rate of the gas supplied to the air port is determined so that the combustion temperature at the upper part of the furnace matches the set value, and the combustion adjustment gas supplied to the burner is set so that the combustion temperature at the lower part of the furnace matches the set value. By determining the oxygen flow rate and subtracting the total oxygen flow rate supplied to the airport and combustion adjustment gas from the total oxygen flow rate determined so that the boiler outlet oxygen average concentration matches the set value, fuel transfer A control method for an oxyfuel boiler plant, characterized by determining an oxygen flow rate of a gas used for the operation. In claim 6,
The control device is
Calculate a future value of the fuel flow rate based on a boiler model that simulates the characteristics of the boiler and a control model that simulates a control operation to the boiler,
Based on the future value of the fuel flow rate, the predicted value of the combustion speed or the combustion temperature is output,
The amount of oxygen or the amount of exhaust gas recirculation is determined by prior control based on the predicted value of the combustion rate or the predicted value of the fuel flow rate.
A control method for an oxyfuel boiler plant, characterized in that: Using a gas containing oxygen at a higher concentration than in air and a gas containing carbon dioxide at a higher concentration than in air, a boiler that generates fuel by burning fuel at a burner and an air port, and a gas containing the carbon dioxide In the display method of the control device of the oxyfuel boiler plant comprising exhaust gas circulating means for using a part of boiler exhaust gas as circulating exhaust gas, and carbon dioxide recovery means for recovering carbon dioxide in the exhaust gas of the boiler,
A database recording the combustion rate or temperature of the fuel;
A database recording the amount of exhaust gas recirculation or oxygen supplied to the burner or the air port;
The display method of the control apparatus which compares and displays the said combustion speed or the said combustion temperature, and the quantity of the said waste gas recirculation, or the quantity of the said oxygen.   11. The display method of the control device according to claim 10, wherein when the comparison is displayed, the display is performed using a time axis as a reference display common to both of the comparisons.   12. The display method of the control device according to claim 11, wherein the reference display is displayed on the basis of a change start time of the combustion speed or a time when a set value of the combustion speed is set.

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